J/ApJ/725/875 Chromospheric activity for CPS stars (Isaacson+, 2010)
Chromospheric activity and jitter measurements for 2630 stars on the California Planet Search. Isaacson H., Fischer D. <Astrophys. J., 725, 875-885 (2010)> =2010ApJ...725..875I
ADC_Keywords: Spectroscopy ; Stars, late-type ; Stars, ages Keywords: stars: activity - stars: chromospheres - stars: fundamental parameters Abstract: We present time series measurements of chromospheric activity for more than 2600 main-sequence and subgiant stars on the California Planet Search (CPS) program with spectral types ranging from about F5V to M4V for main-sequence stars and from G0IV to about K5IV for subgiants. The large data set of more than 44000 spectra allows us to identify an empirical baseline floor for chromospheric activity as a function of color and height above the main sequence. We define ΔS as an excess in emission in the CaII H and K lines above the baseline activity floor and define radial velocity jitter as a function of ΔS and B-V for main-sequence and subgiant stars. Although the jitter for any individual star can always exceed the baseline level, we find that K dwarfs have the lowest level of jitter. The lack of correlation between observed jitter and chromospheric activity in K dwarfs suggests that the observed jitter is dominated by instrumental or analysis errors and not astrophysical noise sources. Thus, given the long-term precision for the CPS program, radial velocities are not correlated with astrophysical noise for chromospherically quiet K dwarf stars, making these stars particularly well suited for the highest precision Doppler surveys. Chromospherically quiet F and G dwarfs and subgiants exhibit higher baseline levels of astrophysical jitter than K dwarfs. Despite the fact that the rms in Doppler velocities is correlated with the mean chromospheric activity, it is rare to see one-to-one correlations between the individual time series activity and Doppler measurements, diminishing the prospects for correcting activity-induced velocity variations in F and G dwarfs. Description: Here we provide updated activity measurements with a calibration of SHK (the ratio of flux in the CaII line cores to flux in nearby continuum regions) to the Mt. Wilson Observatory (MWO) scale for California Planet Search (CPS) spectra of main-sequence and subgiant stars obtained after the upgrade of the Keck/HIRES CCD in 2004 August (resolution R=52000) and activity measurements for stars on the Lick planet search project. The Lick Observatory Planet Search began in 1987 with the Hamilton Spectrometer and both the Shane 3m telescope and the 0.6m Coude Auxiliary Telescope (CAT) (spectral resolution of R=55000 at 6000Å). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 63 2629 S-values and derived quantities table2.dat 49 44188 S-values and Julian Date
See also: III/159 : Ca II H and K Measurements Made at MWO (Duncan+ 1991) J/A+A/520/A79 : FGK stars chromospheric activity (Martinez-Arnaiz+, 2010) J/ApJ/687/1264 : Age estimation for solar-type dwarfs (Mamajek+, 2008) J/A+A/474/293 : Radial velocities of GJ 674 (Bonfils+, 2007) J/A+A/469/309 : Chromospheric activity in late-type stars (Cincunegui+, 2007) J/AJ/123/3356 : Palomar/MSU nearby star spectroscopic survey (Gizis+, 2002) J/A+AS/142/275 : Stellar-activity of late-type stars (Strassmeier+ 2000) J/A+AS/146/103 : CaII H+K to CaII IRT echelle spectra (Montes+, 2000) J/AJ/111/439 : Chromospheric emission in late-type stars. (Henry+ 1996) http://www.exoplanets.org/cps.html : California Planet Survey home page Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 10 A10 --- Name Star name (G1) 12- 17 I6 --- HIP ? Hipparcos identification (NNNNN) 19- 23 F5.3 mag B-V Hipparcos catalog (B-V) color index 25- 30 F6.3 --- SHK Median S_HK_ value (G2) 32- 37 F6.3 m/s Jitter [0/80.14] Radial velocity jitter (1) 39- 45 F7.4 [-] logRHK ? Log of R'_HK_ value (G3) 47- 53 F7.2 mag dMag ? Height above the main sequence (δMV) 55- 56 I2 d Prot [0/48]? Rotational period 58- 61 F4.2 [Gyr] logA [0/8.44]? Log of the age 63 A1 --- Obs [K/L] Observatory code: (K)eck or (L)ick
Note (1): We define jitter as the quadrature difference of velocity rms minus the formal internal errors, equation (6) as below: Jitter=(rms2-σ2)0.5
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 10 A10 --- Name Star name (G1) 12- 17 I6 --- HIP ? Hipparcos identification (NNNNNA) 19- 27 F9.3 d JD Julian Date of observation (JD-2440000) 29- 34 F6.3 --- SHK ? S_HK_ value (G2) 35 A1 --- f_SHK [N] N: indicates a NaN value 37- 42 F6.3 [-] logRHK ? Log of R'_HK_ value (G3) 43 A1 --- f_logRHK [N] N: indicates a NaN value 45- 47 I3 --- SNR Signal-to-noise ratio 49 A1 --- Obs [K/L] Observatory code: (K)eck or (L)ick
Global notes: Note (G1): Star names are HD unless otherwise given. Derived quantities are only given for stars in the range 4.0<logR'HK←5.1. Note (G2): Following a method described in Duncan et al. (1991, Cat. III/159), we measure flux in the core of the CaII H and K lines relative to continuum bands (SHK). See section 2.1 for Keck SHK calibration and text for discussion. Note (G3): To account for different continuum flux levels near the CaII lines for stars of different spectral type, the SHK values are often parameterized as log R'HK, a logarithmic fraction of the flux in the H and K line cores to photometric contributions from the star (Noyes et al. 1984ApJ...279..763N; Middelkoop 1982A&A...107...31M). Because chromospheric activity declines with stellar age, cluster stars have been used to calibrate the logR'HK values to the rotation periods and ages for stars with 0.4<B-V<1.0. See text for further explanations.
History: From electronic version of the journal 29-Aug-2012: HIP 35821 changed in table 1 and 2 for HIP 57370 where Name is HD 102195.
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 08-Aug-2012
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